U.S. patent number 10,280,905 [Application Number 15/514,289] was granted by the patent office on 2019-05-07 for pumping device for a waste heat recovery apparatus in a motor vehicle.
This patent grant is currently assigned to Mahle International GmbH. The grantee listed for this patent is Mahle International GmbH. Invention is credited to Jochen Eggler, Alfred Elsaesser, Helge Ladisch, Christian Maisch, Sascha Senjic.
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United States Patent |
10,280,905 |
Eggler , et al. |
May 7, 2019 |
Pumping device for a waste heat recovery apparatus in a motor
vehicle
Abstract
A pumping device may include a pump housing partially delimiting
a working chamber, and a piston arranged therein, axially movable
between first and second positions in which the working chamber has
maximum and minimum volumes, respectively. The pumping device may
include first and second fluid lines for introducing and
discharging fluid to/from the working chamber, respectively. The
first fluid line may be fluidically connected to the working
chamber via a breakthrough formed in the pump housing at an end
face of the working chamber opposite the piston, running
transversely to the axial direction at least in the area of the
breakthrough. The second fluid line may open obliquely into the
working chamber in an area of the second position, relative to the
axial direction in an end face delimiting the working chamber
towards the first fluid line.
Inventors: |
Eggler; Jochen (Waldburg,
DE), Elsaesser; Alfred (Keltern, DE),
Ladisch; Helge (Stuttgart, DE), Maisch; Christian
(Kirchheim, DE), Senjic; Sascha (Stuttgart,
DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Mahle International GmbH |
Stuttgart |
N/A |
DE |
|
|
Assignee: |
Mahle International GmbH
(DE)
|
Family
ID: |
53783721 |
Appl.
No.: |
15/514,289 |
Filed: |
July 31, 2015 |
PCT
Filed: |
July 31, 2015 |
PCT No.: |
PCT/EP2015/067696 |
371(c)(1),(2),(4) Date: |
March 24, 2017 |
PCT
Pub. No.: |
WO2016/045841 |
PCT
Pub. Date: |
March 31, 2016 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20170298911 A1 |
Oct 19, 2017 |
|
Foreign Application Priority Data
|
|
|
|
|
Sep 25, 2014 [DE] |
|
|
10 2014 219 488 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04B
1/12 (20130101); F04B 11/0091 (20130101); F04B
53/10 (20130101); F03C 1/06 (20130101) |
Current International
Class: |
F04B
1/12 (20060101); F04B 53/10 (20060101); F04B
11/00 (20060101); F03C 1/06 (20060101) |
Field of
Search: |
;417/437,269 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
264295 |
|
Aug 1968 |
|
AT |
|
513999 |
|
Sep 2014 |
|
AT |
|
616208 |
|
Mar 1980 |
|
CH |
|
201277156 |
|
Jul 2009 |
|
CN |
|
3044363 |
|
Jun 1981 |
|
DE |
|
0476450 |
|
Mar 1992 |
|
EP |
|
Other References
English abstract for AT-513999. cited by applicant .
English abstract for CH-616208. cited by applicant .
English abstract for CN-201277156. cited by applicant .
English abstract for EP-0476450. cited by applicant.
|
Primary Examiner: Plakkoottam; Dominick L
Assistant Examiner: Tremarche; Connor J
Attorney, Agent or Firm: Fishman Stewart PLLC
Claims
The invention claimed is:
1. A pumping device for a waste heat recovery apparatus of a motor
vehicle, comprising: a pump housing partially delimiting a working
chamber that is fillable with a fluid; a piston arranged in the
working chamber and movable along an axial direction between a
first position where the working chamber has a maximum volume and a
second position where the working chamber has a minimum volume; a
first fluid line for introducing the fluid into the working
chamber; the first fluid line fluidically connected to the working
chamber via a breakthrough disposed in the pump housing at an end
face of the working chamber opposite the piston; a first valve
element for a fluid-tight closure of the first fluid line with
respect to the working chamber provided in an area of the
breakthrough in the first fluid line; wherein the first fluid line
extends transversely to the axial direction at least in the area of
the breakthrough; a fluid supply line for introducing the fluid
into the first fluid line, the fluid supply line arranged to open
tangentially into the first fluid line, where, from a top view of
the pumping device, a centerline of the fluid supply line is
tangential to a centerline of the first fluid line; a second fluid
line for discharging the fluid from the working chamber, the second
fluid line arranged to open into the working chamber in an area of
the second position of the piston; a second valve element for a
fluid-tight closure of the second fluid line with respect to the
working chamber provided in an opening area of the second fluid
line into the working chamber; wherein the second fluid line opens
obliquely into the working chamber relative to the axial direction;
wherein the second valve element communicates fluidically with the
working chamber directly without defining an intermediate space;
wherein the second fluid line opens into the working chamber in an
axial end section of the working chamber towards the first fluid
line; wherein the pump housing includes a circumferential wall
providing a circumferential-side delimitation of the working
chamber and an end wall providing an end-face-side delimitation of
the working chamber towards the first fluid line, and the second
fluid line has an opening orifice disposed in at least one of the
circumferential wall and the end wall; wherein the second valve
element is structured and arranged to open and close the opening
orifice of the second fluid line and define part of at least one of
the circumferential-side delimitation and the end-face-side
delimitation; and wherein the first fluid supply line opens
obliquely into the first fluid line.
2. The pumping device according to claim 1, wherein the first fluid
line extends in the area of the breakthrough in a plane
perpendicular to the axial direction and has a curved portion at
least in the area of the breakthrough.
3. The pumping device according to claim 2, wherein the first fluid
line is configured as a closed annular fluid channel that extends
completely in the plane perpendicular to the axial direction.
4. The pumping device according to claim 1, wherein the first valve
element projects at least partially from the first fluid channel
through the breakthrough and into the working chamber.
5. The pumping device according to claim 1, wherein the first valve
element is arranged completely in the working chamber and
communicates fluidically via the breakthrough directly with the
first fluid line.
6. The pumping device according to claim 1, wherein the first fluid
line provides an extension of the working chamber along the axial
direction.
7. The pumping device according to claim 1, wherein the first valve
element is a non-return valve adjustable between an open position
and a closed position, wherein the non-return valve is adjusted
from the closed position into the open position when the fluid
pressure in the first fluid line is greater than in the working
chamber and the pressure difference between the fluid in the
working chamber and the fluid in the first fluid line exceeds a
predetermined threshold value.
8. The pumping device according to claim 1, wherein the first valve
element is a non-return valve adjustable to open and close the
breakthrough, and wherein the first valve element is arranged to
communicate fluidically via the breakthrough directly with the
first fluid line without defining an intermediate space.
9. The pumping device according to claim 1, wherein the opening
orifice of the second fluid line is disposed in a transition region
between the circumferential wall and the end wall, and wherein the
second valve element defines part of the circumferential-side
delimitation and the end-face-side delimitation of the working
chamber.
10. The pumping device according to claim 1, wherein the second
valve element ends substantially flush with the at least one of the
circumferential wall and the end wall.
11. A pump arrangement, comprising: a pump housing; a plurality of
pumping devices disposed in the pump housing, the plurality of
pumping devices respectively including: a working chamber at least
partially delimited by the pump housing that is fillable with a
fluid; a piston arranged in the working chamber and movable along
an axial direction between a first position where the working
chamber has a maximum volume and a second position where the
working chamber has a minimum volume; a first fluid line for
introducing the fluid into the working chamber; a breakthrough
disposed in the pump housing fluidically connecting the first fluid
line to the working chamber, the breakthrough disposed in the pump
housing at an end face of the working chamber opposite the piston,
wherein the first fluid line extends transversely to the axial
direction at least in an area of the breakthrough; a first valve
element for a fluid-tight closure of the first fluid line with
respect to the working chamber provided in the area of the
breakthrough in the first fluid line; a fluid supply line for
introducing the fluid into the first fluid line, the fluid supply
line arranged to open tangentially into the first fluid line,
where, from a top view of the pump arrangement, a centerline of the
fluid supply line is tangential to a centerline of the first fluid
line; a second fluid line for discharging the fluid from the
working chamber, the second fluid line arranged to open into the
working chamber in an area of the second position of the piston,
wherein the second fluid line opens obliquely into the working
chamber relative to the axial direction; a second valve element for
a fluid-tight closure of the second fluid line with respect to the
working chamber provided in an opening area of the second fluid
line into the working chamber, the second valve element
communicating fluidically with the working chamber directly without
defining an intermediate space; wherein the second fluid line opens
into the working chamber at an axial end section of the working
chamber towards the first fluid line; wherein the working chambers
of the plurality of pumping devices define an arrangement with each
of the breakthroughs arranged parallel to one another in relation
to the axial direction; wherein the arrangement of the working
chambers with the breakthroughs has a 120.degree. rotational
symmetry in a cross-section perpendicular to the axial direction in
relation to a predefined symmetry point; wherein the first fluid
lines of the plurality of pumping devices define a common annular
fluid channel with the predefined symmetry point providing an
annular centre point of the annular fluid channel; and wherein the
first fluid supply line opens obliquely into the first fluid
line.
12. The pump arrangement according to claim 11, wherein the
plurality of pumping devices includes three pumping devices.
13. The pump arrangement according to claim 11, wherein the working
chambers of the plurality of pumping devices are respectively
delimited by a circumferential wall of the pump housing providing a
circumferential-side delimitation and an end wall of the pump
housing providing an end-face-side delimitation towards the first
fluid line; and wherein the second fluid line of at least one of
the plurality of pumping devices has an opening orifice disposed in
a transition region between the circumferential wall and the end
wall, and the second valve element of the at least one of the
plurality of pumping devices is structured and arranged to open and
close the orifice opening and define part of the
circumferential-side delimitation and the end-face-side
delimitation.
14. The pump arrangement according to claim 13, wherein the second
valve element of the at least one of the plurality of pumping
devices ends substantially flush with at least one of the
circumferential wall providing the circumferential-side
delimitation and the end wall providing the end-face-side
delimitation.
15. A waste heat recovery apparatus, comprising: a fluid cycle for
communicating a fluid flow; a pumping device arranged for driving a
fluid in the fluid cycle, the pumping device including: a pump
housing partially delimiting a working chamber that is fillable
with a fluid; a piston arranged in the working chamber and movable
along an axial direction between a first position where the working
chamber has a maximum volume and a second position where the
working chamber has a minimum volume; a first fluid line for
introducing the fluid into the working chamber; a breakthrough
disposed in the pump housing fluidically connecting the first fluid
line to the working chamber, the breakthrough disposed in the pump
housing at an end face of the working chamber opposite the piston,
wherein the first fluid line extends transversely to the axial
direction at least in an area of the breakthrough; a first valve
element for a fluid-tight closure of the first fluid line with
respect to the working chamber provided in the area of the
breakthrough in the first fluid line; a fluid supply line for
introducing the fluid into the first fluid line, the fluid supply
line arranged to open tangentially into the first fluid line,
where, from a top view of the pumping device, a centerline of the
fluid supply line is tangential to a centerline of the first fluid
line; a second fluid line for discharging the fluid from the
working chamber, the second fluid line arranged to open into the
working chamber in an area of the second position of the piston,
wherein the second fluid line opens obliquely into the working
chamber relative to the axial direction; a second valve element for
a fluid-tight closure of the second fluid line with respect to the
working chamber provided in an opening area of the second fluid
line into the working chamber, the second valve element
communicating fluidically with the working chamber directly without
defining an intermediate space; a first resilient element and a
second resilient element arranged in the working chamber, the first
resilient element being supported at one end on the first valve
element and configured to pre-tension the piston towards the first
position, the second resilient element being arranged at an end of
the working chamber opposite to the first valve element; wherein
the second fluid line opens into the working chamber at an axial
end section of the working chamber towards the first fluid line;
wherein the first valve element is adjustable to open and close the
breakthrough, and the first valve element is arranged to
communicate fluidically via the breakthrough directly with the
first fluid line without defining an intermediate space between the
first valve element and the breakthrough; and wherein the first
fluid supply line opens obliquely into the first fluid line.
16. The waste heat recovery apparatus according to claim 15,
wherein the pumping device includes three pumping devices disposed
in an arrangement such that the breakthrough of each of the three
pumping devices are parallel to one another in relation to the
axial direction.
17. The waste heat recovery apparatus according to claim 16,
wherein the arrangement has a 120.degree. rotational symmetry in a
cross-section perpendicular to the axial direction in relation to a
predefined symmetry point; and wherein the first fluid line of each
of the three pumping devices define a common annular fluid channel
with the symmetry point providing an annular centre point of the
annular fluid channel.
18. The waste heat recovery apparatus according to claim 15,
wherein the first fluid line extends in the area of the
breakthrough in a plane perpendicular to the axial direction and
has a curved portion at least in the area of the breakthrough.
19. The waste heat recovery apparatus according to claim 15,
wherein the first valve element is arranged completely in the
working chamber.
20. The waste heat recovery apparatus according to claim 15,
wherein: the first valve element and the second valve element are
each adjustable between an open position and a closed position; the
first valve element is adjusted from the closed position into the
open position when a fluid pressure in the first fluid line is
greater than a fluid pressure in the working chamber and a pressure
difference between the fluid pressure in the first fluid line and
the fluid pressure in the working chamber exceeds a first
predetermined threshold value; and the second valve element is
adjusted from the closed position into the open position when the
fluid pressure in the working chamber is greater than a fluid
pressure in the second fluid line and a pressure difference between
the fluid pressure in the working chamber and the fluid pressure in
the second fluid line exceeds a second predetermined threshold
value.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority to German Patent Application No.
10 2014 219 488.1, filed on Sep. 25, 2014, and International Patent
Application No. PCT/EP2015/067696, filed Jul. 31, 2015, the
contents of which are hereby incorporated by reference in their
entirety.
TECHNICAL FIELD
The invention relates to a pumping device, in particular an axial
piston pump, for a waste heat recovery apparatus in a motor
vehicle.
BACKGROUND
Waste heat recovery devices are used for recovering energy from a
waste heat flow of an internal combustion engine of a motor
vehicle. Waste heat recovery devices known from the prior art
typically comprise a fluid cycle, for example, a so-called
Clausius-Rankine cycle in which a working fluid circulates.
Mechanical energy is obtained from the heat stored in the working
medium by various changes in state in the working fluid to which
this is subjected when flowing through the fluid cycle.
Pumping devices are used for transporting the working fluid, which
for example can be implemented in the form of a so-called stroke or
axial piston pump. Such a stroke or axial piston pump follows the
principle of action of a displacement pump in which the so-called
displacer in the form of a piston executes a translational stroke
movement within a working volume.
Against this background U.S. Pat. No. 3,412,453 A and U.S. Pat. No.
4,486,152 A each disclose a pumping device having a working chamber
in which a piston is arranged adjustably. A first fluid line is
used to introduce a fluid into the working chamber and is
fluidically connected to the working chamber by means of a
breakthrough arranged on an end face of the working chamber
opposite the piston. A first valve element for closing the first
fluid line with respect to the working chamber is arranged in the
area of the breakthrough.
In addition, a second fluid line opens into the working chamber via
which the fluid can again be discharged from the working chamber
and specifically in the region of a position of the piston in which
the working chamber has a minimal volume. A second valve element
for closing the second fluid channel towards the working chamber is
provided in the opening area of the second fluid line into the
working chamber.
Cavitation effects which occur during the conveyance of the working
fluid in the working volume frequently prove to be problematical in
these stroke piston pumps. These typically result in a reduction in
the amount of fluid conveyed by the pump within the stroke cycle.
In extreme cases as a result of such cavitation, even individual
components of the pumping device in contact with the working fluid
such as, for example, valve elements or similar can be irreversibly
damaged.
It is therefore an object of the present invention to provide an
improved embodiment for a pumping device in which the said problems
no longer occur or at most in severely restricted form.
The object is solved by the subject matter of the independent
claim(s). Preferred embodiments are the subject matter of the
dependent claims.
SUMMARY
The basic idea of the invention is accordingly to introduce the
fluid to be conveyed by the pumping device from a fluid line into a
working chamber of the pump which is fluidically connected to the
working chamber at an end face of said working chamber. In this
case, in relation to an axial direction along which a piston of the
pumping device is adjustable in the working chamber, the end face
lies opposite this piston. Said fluid line--hereinafter designated
as "first fluid line"--is fluidically connected to the working
chamber of the pumping device by means of a breakthrough provided
in the pump housing of the pumping device.
It is essential to the invention that the arrangement of the first
fluid line relative to the working chamber is in such a manner that
it extends at least in the area of the breakthrough transversely to
the axial direction. Experimental investigations have revealed that
in this way flow losses in particular in the orifice area of the
first fluid line can be reduced or even completely prevented. Since
these flow losses and an associated falling below the vapour
pressure in the working fluid are an essential cause of the
occurrence of undesired cavitation, these cavitation effects can be
prevented in this way. As a result, this leads to an improved
conveying capacity and also to an increased lifetime of the pumping
device.
A pumping device according to the invention comprises a working
chamber which is delimited in part by a pump housing which can be
filled in a known manner with a working fluid--hereinafter for
simplicity designated as "fluid". A piston is arranged so that it
can be moved along an axial direction in the working chamber
forming the working volume. This piston can be moved along an axial
direction between a first position in which the working chamber has
a maximum volume and a second position in which the working chamber
has a minimum volume. A first fluid line is used for introducing
the fluid into the working chamber. Here the first fluid line is
fluidically connected to the working chamber by means of a
breakthrough which is formed in the pump housing at an end face of
the working chamber opposite the piston. A first valve element for
closing the first fluid line with respect to the working chamber is
provided in the area of the breakthrough. The first fluid line runs
transversely to the axial direction at least in the area of the
breakthrough.
According to the invention, the second valve element communicates
fluidically directly with the working chamber to avoid dead
volumes. According to the invention, the second fluid line opens
into the working chamber in an end facedelimiting the working
chamber towards the first fluid line. In this way, the pumping
device according to the invention can have a constructively
particularly simple structure which is associated with reduced
manufacturing costs.
In a preferred embodiment, the pumping device can comprise a fluid
supply line for introducing the fluid into the first fluid line,
which opens tangentially and/or obliquely into the first fluid
line. Both measures, taken for themselves or in combination, have
the result that the fluid can be introduced into the first fluid
line without any defined deflection of the flow direction from the
fluid supply line. Thus, undesired pressure losses in the fluid
during introduction into the first fluid line and consequently also
the formation of cavitation can be largely or even completely
prevented.
Particularly little installation space is required by the pumping
device according to the invention according to a further preferred
embodiment in which the first fluid line extends in the area of the
breakthrough in a plane perpendicular to the axial direction and is
configured to be curved at least in the area of the
breakthrough.
In a further preferred embodiment, the first fluid line is
configured as a closed annular fluid channel which extends
completely in the plane perpendicular to the axial direction. Such
an annular geometry of the first fluid line has the result that the
average transverse acceleration acting on the fluid during flow
through the fluid channel can be kept relatively low. This measure
also has the result that a pressure drop in the fluid caused by
high transverse accelerations is largely avoided.
In another preferred embodiment, the first valve element projects
at least partially from the first fluid channel through the
breakthrough into the working chamber. This means that no
additional fluid line needs to be provided between the first fluid
line and the working chamber but that the fluid can be introduced
directly from the--preferably annular--first fluid line into the
working chamber of the pumping device. In this way, the amount of
fluid to be accelerated during suction of the fluid into the
working chamber is minimized, with the result that the already
explained pressure drop of the fluid pressure, in this case caused
by acceleration, can be reduced still further.
Particularly expediently the first valve element is a non-return
valve which is adjustable between an open and a closed position,
which is adjusted from the closed into the open position when the
fluid pressure in the first fluid line is greater than in the
working chamber and the pressure difference exceeds a predetermined
threshold value. The use of such a constructively simply
constructed non-return valve has the result that flow losses in the
area of the valve element can be further reduced.
In order to discharge the fluid from the working chamber, in a
further preferred embodiment it is proposed to fit the pumping
device with a second fluid line for discharging the fluid from the
working chamber. This preferably opens into the working chamber in
the area of the second position of the piston. Similarly to the
first fluid line, a valve element--hereinafter designated as
"second valve element"--is provided for closure of the second fluid
line in an opening area of the second fluid line into the working
chamber.
In a further preferred embodiment, the opening area of the second
fluid line is provided in an axial end section of the working
chamber facing the first fluid line. This means that the two fluid
lines open adjacently to one another into the working chamber of
the pump. Thus, flow losses promoting the occurrence of cavitation
can be restricted to a spatially limited area of the working
chamber.
A further preferred embodiment in which the second fluid line opens
into the working chamber in a circumferential side delimiting the
working chamber and/or in an end face of the housing delimiting the
working chamber towards the first fluid line has a constructively
particularly simple structure and is thus associated with reduced
manufacturing costs.
In a further preferred embodiment, the second valve element forms a
part of the circumferential-side and/or end-face-side delimitation
of the working chamber. Experimental tests have shown that such an
arrangement particularly effectively counteracts cavitation
effects.
Particularly expediently, the second valve element can end
substantially flush with an end face and/or circumferential side
delimiting the working chamber towards the first fluid line. An
undesired recess promoting the formation of cavitation can in this
way be largely or even completely avoided.
Experimental investigations and theoretical simulation calculations
have shown that a particularly favourable flow pattern with regard
to undesired cavitation formation can be produced in the working
volume if the second fluid line opens obliquely into the working
chamber relative to the axial direction.
According to a further preferred embodiment, the first fluid line
is arranged in such a manner that the first fluid line extends or
lengthens the working chamber along the axial direction.
Similarly to the first valve element, in a further preferred
embodiment the second valve element can be a non-return valve which
is adjustable between an open and a closed position. The second
non-return valve is then adapted in such a manner that it is
adjusted from the closed into the open position when the fluid
pressure in the working chamber is greater than in the second fluid
line and the pressure difference exceeds a predetermined threshold
value. Accordingly, the second non-return valve can be reset into
the closed position when the pressure difference again drops below
said threshold value.
In another preferred embodiment, an orifice opening of the second
fluid line into the working chamber can be arranged with regard to
its axial position in such a manner that the piston specifically
does not close this in its second position.
In a further preferred embodiment, the first valve element projects
into the working chamber in such a manner that the remaining volume
between the piston in its second position and the first valve
element adopts a minimum value. This measure also counteracts
undesired flow and compression losses of the fluid in the working
volume.
In order to assist the introduction of fluid into the working
chamber and the associated translational movement away from the
opening of the first fluid line, a resilient element can be
provided in the working chamber. This is preferably supported at
one end on the first valve element and at the other end on the
piston and thus pretensions the piston towards the first
position.
If the conveying capacity desired in a specific application exceeds
the conveying capacity which can actually be provided by the
pumping device according to the invention, it is possible to set a
plurality of pumping devices according to the invention in
operative connection with one another and connect these fluidically
in parallel to increase the conveying capacity. The invention
therefore also relates to a pump arrangement comprising three
previously introduced pumping devices according to the invention,
whose working chambers are arranged with the breakthroughs between
working chamber and first fluid line in each case parallel to one
another in relation to the axial direction. The arrangement of the
three working chambers with the breakthroughs between the first
fluid line and the working chamber has a 120.degree. rotational
symmetry in a cross-section perpendicular to the axial direction in
relation to a predefined symmetry point. Accordingly, the three
first fluid lines are formed as a common annular fluid channel with
the already-mentioned symmetry point as the annular centre point of
the annular fluid channel. In this way, the installation space
required for the three pumping devices can be kept small. The
symmetrical structure of the three pumping devices also has the
result that when three pumping devices are fluidically
interconnected, the occurrence of undesired cavitation can be
largely or completely avoided.
The invention finally relates to a waste heat recovery apparatus,
comprising a fluid cycle through which a working medium--a
fluid--flows or can flow. A pumping device according to the
invention introduced above or a previously introduced pump
arrangement according to the invention comprising three pumping
devices is arranged in the fluid cycle for driving the working
medium.
Further important features and advantages of the invention are
obtained from the subclaims, from the drawings and from the
relevant description of the figures with reference to the
drawings.
It is understood that the features mentioned previously and to be
explained further hereinafter can be used not only in the
respectively given combination but also in other combinations or
alone without departing from the scope of the present
invention.
Preferred exemplary embodiments of the invention are presented in
the drawings and are explained in detail in the following
description, where the same reference numbers relate to the same or
similar or functionally the same components.
BRIEF DESCRIPTION OF THE DRAWINGS
In the figures, in each case schematically:
FIG. 1 shows an example of a pump arrangement according to the
invention in a perspective view,
FIG. 2 shows a detailed view of FIG. 1 in which the structure of a
pumping device 1 of the pump arrangement is shown in detail,
FIG. 3 shows a detailed view of the pumping device of FIG. 2 in the
area of a working chamber 3 of the pumping device 1,
FIG. 4 shows a schematic view illustrating the tripod-like
structure of the three pumping devices of FIG. 1 in schematic
form.
DETAILED DESCRIPTION
FIG. 1 illustrates in a perspective view an example of a pump
arrangement 20 according to the invention. FIG. 2 shows a detailed
view of FIG. 1 in which the structure of a pumping device 1 of the
pump arrangement 20 is shown in detail. FIG. 3 in turn shows a
detailed view of FIG. 2 in the area of a working chamber 3 of the
pumping device 1.
The pump arrangement 20 comprises three pumping devices 1 each
configured as stroke or axial piston pumps, which are implemented
to form the pump arrangement 20 in the form of a tripod
arrangement. This means that the respective pistons 2 of the three
pumping devices 1 and the working chambers 3 accommodating the
respective pistons 2, which are each delimited by a pump housing 4
are arranged parallel to one another in relation to their axial
axis. A piston 2 which can be adjusted along an axial direction A
is arranged in each of the three working chambers 3. Each of the
three pistons 2 is adjustable axially between a first position in
which the working chamber 3 has a maximum volume and a second
position in which the working chamber 3 has a minimum volume. A
common electric motor 22 which is arranged in a motor housing 21
which extends the pump housing 4 contrary to the axial direction A
is used to adjust the three pistons 3. The electric motor 22 can be
controlled with the aid of an electric/electronic control unit 25
which is fastened to this on a side of the motor housing 22 facing
away axially from the pump housing 4.
The structure of one of the three pumping devices 1 is explained in
detail hereinafter with reference to the diagram in FIG. 2.
The pump housing 4 together with the piston 2 delimits the working
chamber 3 which can be filled with a fluid--the working medium of
the pumping device 1. For this purpose the pumping device 1 has a
first fluid line 5 which is fluidically connected to the working
chamber 3 by means of a breakthrough 9. The breakthrough 9 is
formed in the pump housing 4 on an end face 7 of the working
chamber 3 opposite the piston 2. The first fluid line 5 runs in the
area of the breakthrough 9 transversely to the axial direction A.
In this case, the first fluid line 5 extends in the area of the
breakthrough 9 in said plane perpendicular to the axial direction
A.
In the example of the figures the first fluid line 5 is configured
as a closed annular fluid channel 23 which extends completely in a
plane perpendicular to the axial direction A. Consequently the
first fluid line 5 is configured to be curved in the area of the
breakthrough 9.
In the area of the breakthrough 9 a first valve element 10 for
closing the first fluid line 5 is provided in the working chamber
3. In one variant the first valve element 10 can be arranged in the
area of the breakthrough 9 also on the side of the first fluid line
5. The first valve element 10 in one variant can also project from
the first fluid line 5 through the breakthrough 9 into the working
chamber 3 and specifically in such a manner that the dead volume of
the working chamber 3 is minimal or even has a zero value.
Unnecessary dead volumes can also be avoided if the first valve
element 10 communicates fluidically directly with the first fluid
line 5, i.e. no intermediate space is formed between the first
fluid line 5 and the first valve element 10.
The formation of undesired dead volumes can also be counteracted in
the variant shown in the figures in which the first valve element
10 is arranged completely in the working chamber 3 and communicates
fluidically via the breakthrough 9 directly, i.e. without forming
an intermediate space, with the first fluid line 5.
In the example of the figures, the first valve element 10 is a
non-return valve 11 which is adjustable between an open and a
closed position. In the closed position the first valve element 10
closes the first fluid line 5 with respect to the working chamber 3
in a fluid-tight manner. In the open position the first valve
element 10 releases the fluid communication between first fluid
line 5 and the working chamber 3 so that the fluid can be
introduced from the first fluid line 5 into the working chamber 3.
The non-return valve 11 is adjusted from its closed position into
its open position when the fluid pressure in the first fluid line 5
is greater than in the working chamber 3 and the pressure
difference exceeds a predetermined value. This takes place by an
axial movement of the piston 2 away from the breakthrough 9.
According to FIG. 2, the pumping device 1 also comprises a fluid
supply line 24 for introducing the fluid into the first fluid line
5. According to FIG. 2, the first fluid line 5 extends the working
chamber 3 along the axial direction A. The fluid supply line 24
opens tangentially into the first fluid line 5 configured as
annular fluid channel 23. Alternatively or additionally the fluid
supply line 24 can also open obliquely into the first fluid line 5.
This can in particular mean that in a longitudinal section of the
pumping device 1 along the axial direction A the fluid supply line
24 forms an acute angle with the plane perpendicular to the axial
direction A in which the annular fluid channel 23 is arranged.
For discharging the fluid from the working chamber 3, a second
fluid line 6 is provided which opens into the working chamber 3 in
the area of the second position of the piston 2--this position is
shown in FIG. 2 and also in the detailed view of FIG. 3. The
opening area 12 of the second fluid line 6 is therefore--in the
same way as the first fluid line 5 arranged on the front
side--arranged in an axial end section 14 of the working chamber 3
facing the first fluid line 5. The second fluid line 6 opens into
the working chamber 3 in a transition region between a
circumferential wall 15 of the pump housing 4 delimiting the
working chamber 3 and an end wall delimiting the pump housing 4
towards the first fluid line 5. The second fluid line 6 opens
obliquely into the working chamber 3 relative to the axial
direction A. An orifice opening 16 of the second fluid line 6 is
arranged in relation to its axial position in such a manner that
the piston 2 specifically does not close the orifice opening 16 in
its second position.
Corresponding to the breakthrough 9 of the first fluid line 5, a
second valve element 13 for optional fluid-tight closure of the
second fluid line 6 with respect to the working chamber is also
provided in the orifice area 12 of the second fluid line 6 into the
working chamber 3. The second valve element 13, in the same way as
the first valve element 10, is implemented as a non-return valve
17. In contrast to the first valve element 10 however it is
adjusted from the closed into the open position when the fluid
pressure in the working chamber 3 is greater than in the second
fluid line and the pressure different exceeds a predetermined
threshold value. This takes place if the piston 2 is moved along
the axial direction A towards the breakthrough 9.
In the example of the figures, the second valve element 13 which is
arranged in the transition region between circumferential-side and
end-face-side delimitation of the working chamber 3, forms a part
of the circumferential-side and end-face-side delimitation of the
working chamber 3. Ideally the second valve element 13 ends
substantially flush with the end face and/or circumferential side
delimiting the working chamber 3 towards the first fluid line 5. An
undesired recess promoting the formation of cavitation can in this
way be largely or even completely avoided.
As shown in FIGS. 2 and 3, a resilient element 19 can be provided
in the working chamber 3. This is supported according to FIG. 3 at
one end on the first valve element 10 and at the other end on the
piston 2 and thus pre-tensions the piston 2 towards the first
position.
Finally, the already-mentioned tripod-like arrangement of the pump
arrangement 20 is explained with reference to FIG. 4. To this end,
FIG. 4 shows the structure of FIG. 2 in a cross-section
perpendicular to the axial direction A in a roughly schematic view.
The three working chambers 3 of the three pumping device
1--indicated by dashed lines in FIG. 4--are arranged parallel to
one another along the axial direction A. As FIG. 4 clearly
confirms, the arrangement of the three working chambers 3 in the
cross-section perpendicular to the axial direction A exhibits a
120.degree. rotational symmetry in relation to a predefined
symmetry point S. The three first fluid lines 5 here are formed as
a common annular fluid channel 23 with the symmetry point S as
annular central point M. The fluid channel 23 can be arranged in a
plane perpendicular to the axial direction A.
In this way, the formation of the first fluid line 5 as an annular
fluid channel 23 can be used to supply the working chambers 3 of
all three pumping devices 1 with the working medium in the manner
described above. This ensures that the formation of undesired
cavitation both in the fluid channel 23 and in the three working
chambers 3 can be largely or even completely prevented.
The three second fluid lines 6 open according to FIG. 2 into a
common fluid discharge line 8.
* * * * *